(5) 
of the horizontal part, or in other words solid mixed crystals were 
obtained, the HM F of which was different from that of an amalgam 
represented by the horizontal line and which reached equilibrium 
much less rapidly than the semi-liquid amalgams. 
Microbiology. — “Further Researches concerning Oligonitroph- 
ilous Microbes.” By Prof. M. W. BEIJERINCK. 
In my first paper on oligonitrophilous microbes!) I still left the 
question unanswered after the forms which develop in the light, 
in nutrient liquids, which only contain traces of nitrogen compounds, 
and whose nutrition with carbon can only be effected from the 
carbonic acid of the air. 
The experiments to answer this question were made as follows. 
Large flasks were plugged with cotton wool or filtering paper, so 
that the air has free access, or closed in such a way that the air 
could be renewed, and that, at each renewing, it must pass through 
strong sulphuric acid in order to be deprived of the nitrogen- 
compounds. These flasks had been half filled with 
100 Tap- or distilled water 
0.02 K? H PO* 
and infected with a not too slight quantity of garden-soil, e.g. 1 to 
2 grs. per liter ®). 
They were placed in winter at a window on the south, in spring 
and in summer on the north-west, and in the beginning they were 
now and then shaken, in order to sink the floating film of calcium- 
phosphate, which forms at the surface. 
As the rate of nitrogen and carbon compounds is too slight 
to cause any appreciable development of colourless microbes, no 
further cloudiness results, but that of the easily precipitating 
phosphate. But in winter after six to eight, in summer after four 
to five weeks, a characteristic flora develops consisting of some species 
1) These Proceedings of March 30, 1901. 
2) The Delft tap-water contains at present 0.42 mG. nitrogen per L., the garden- 
soil used 0,56 pCt. nitrogen (analyses of Mr. A. v. Drrpen), but this nitrogen can 
only for a minimal portion (as ammonia and nitrate—nitrogen) be assimilated by microbes, 
The oligonitrophili themselves possess the specific faculty of feeding on the nitrogen 
from the atmosphere. 
